From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The performance, construction, and cost of a by-pass oil filter.
| Identifier | ExFiles\Box 140\3\ scan0173 | |
| Date | 13th June 1938 | |
| -2- Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}7/MH.{M. Huckerby}13.6.38. This filter shows up favourably with other comparative by-pass filters and is approximately 25% better than its nearest rival. Regarding its capacity we have found that it is capable of cleaning 4 gallons of dirty oil at 25% to oil at 75%, 100% being the figure for new oil. When choked up with dirt the filter cartridge which is spring loaded, lifts and allows oil to bye-pass to the return outlet. From American figures the initial cost is 7/od. complete and renewal cartridge element 1/od. It has the advantage that the cartridge is easily interchangeable and does not necessitate any spannering etc. Regarding its construction, the oil inlet at the base passes through a moulded charcoal cone, thence through a cell of cotton waste and finally through fine cotton linters to the outlet. A cartridge lasts us over a 10,000 mile test at which time the oil begins to get dirty again, from the amber colour which maintains whilst the filter is working. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||